When Proceed to check out button is selected you will need to either checkout as a Guest, or Register an account. See above image.

Fill in your delivery details the select or deselect "I also want to ship to this address"

Above image: fill in your delivery details

Note: The shipping cost is processed in real time by Australia Post. If the address you entered comes back as incorrect, try entering it another way, as this means Australia Post does not recognise the inputed address.